Kinematic extensible truss mechanism

ABSTRACT

A kinematic extensible truss mechanism comprising a first set of truss members arranged in a parallelogram with pivots at each of the junctures of the truss members, and a second set of truss members arranged in a parallelogram with pivots at each of the junctures of the second set of truss members. Two of the pivots of the first set coincide with two of the pivots of the second set, and at least one rigid extension projects from one of the truss members of the second set substantially at right angles thereton. An arm is pivotally connected to the rigid extension and connected for rotation to a pivot of the first set of truss members which is not common to the first and second set of truss members. In this manner movement of one of the truss members of one of the sets relative to another member of the other of the sets maintains parallelism of the one truss member to the other when relative motion occurs in a first direction, and results in an elevation of the one relative to the other when relative motion occurs in the opposite direction.

United States Patent 1191 Smith Jan. 1,1974

[ KINEMATIC EXTENSIBLE TRUSS MECHANISM Roy Richard Smith, Poughkeepsie,NY.

[73] Assignee: International Business Machines Corporation, Armonk, NY.

[22] Filed: Oct. 17, 1972 [21] Appl. No.: 298,319

[75] Inventor:

[52] US. Cl 248/370, 14/5, 248/284,

248/419, 248/424 [51] Int. Cl. F16m 13/00, EOld 15/00 [58] Field ofSearch 248/270, 280, 281,

Primary Examiner-Allan D. Herrmann Att0rney-Wil1iam .1. Dick et a1.

[57] ABSTRACT A kinematic extensible truss mechanism comprising a firstset of truss members arranged in a parallelogram with pivots at each ofthe junctures of the truss members, and a second set of truss membersarranged in a parallelogram with pivots at each of the junctures of thesecond set of truss members. Two of the pivots of the first set coincidewith two of the pivots of the second set, and at least one rigidextension projects from one of the truss members of the second setsubstantially at right angles thereton. An arm is pivotally connected tothe rigid extension and connected for rotation to a pivot of the firstset of truss members which is not common to the first and second set oftruss members. In this manner movement of one of the truss members ofone of the sets relative to another member of the other of the setsmaintains parallelism of the one truss member to the other when relativemotion occurs in a first direction, and results in an elevation of theone relative to the other when relative motion occurs in the oppositedirection.

11 Claims, 8 Drawing Figures KINEMATIC EXTENSIBLE TRUSS MECHANISM Thepurpose of this abstract is to enable the public and the Patent Officeto determine rapidly the subject matter of the technical disclosure ofthe application. This abstract is neither intended to define theinvention of the application nor is it intended to be limiting as to thescope thereof.

SUMMARY OF THE INVENTION AND STATE OF THE PRIOR ART The presentinvention relates to truss mechanisms and more particularly relates to akinematic extensible truss mechanism in which the moving supportmaintains parallelism relative to the fixed support when the firstsupport is extended.

Relay racks utilized in machine controls as by a computer, or relaysthat are energized by and for the computer, are typically kept indrawers which may be extended from their home or nested positionoutwardly so that the various parts therein may be more readilyserviced. Conventionally these relay racks or drawers are extremelyheavy and tend to drop at their outer end when extended full length.This means that in order to reposition the drawer or rack in its home ornested position, after repair or servicing has been carried out, thatthe technician or engineer accomplishing such servicing must lift theend of the rack or drawer prior to reinserting the same into its homeposition. If the rack is heavy (and in most instances it is) the liftingof the end of the rack and sliding the same into its nested position canonly be accomplished with difficulty.

The design of the extensible truss mechanism of the present invention,it has been discovered, may have many uses. For example, with the properstructural material, the mechanism may be useful as a portable bridge,easily put together in the field, and easily movable between an extendedand retracted position. Additionally, it has been discovered thatextension of the first support of the extensible truss mechanism in onedirection relative to the second support thereof (which may be fixed),not only maintains its parallelism with respect to the second supportbut also maintains its position with regard to height above the secondsupport, when extended in the one direction.

It was also discovered that while extending the first support in a firstdirection the parallelism and height above any fixed norm is maintained,an extension of the support in the opposite direction effects anelevation of the first support while maintaining parallelism. Thus thetruss mechanism may be useful for applications such as loading orunloading docks or other elevated platforms by merely loading the firstsupport in its extended and elevated position and then permitting thesupport to move downwardly, while maintaining parallelism with thesecond support, until the support is at its lowest level. Of course,inversion of the structure also results in a structure for elevating orraising the first support from a low position to a raised position.

Additionally, after the structure was developed, it was recognized thatinverting the structure and providing a plurality of the same nestedtogether permits the formation of nestable steps merely by extending thefirst support relative to the second support into the second direction.

In view of the above it is a principal object of the present inventionto provide a kinematic extensible truss mechanism which isself-supporting and which maintains the parallelism of the first supportof the structure relative to the second support of the structure whenthe first support is moved relative to the second support in eitherdirection.

Another object of the present invention is to provide a kinematicextensible truss mechanism in which extension of the truss mechanism ofthe support of the truss mechanism in a first direction maintains thesupport parallel to a norm and at a constant elevation with respectthereto.

Yet another object of the present invention is to provide a kinematicextensible truss mechanism wherein the first support, when moved in adirection opposite to the first direction remains parallel to a fixednorm while increasing its elevation with respect thereto.

Still another object of the present invention is to provide a kinematicextensible truss mechanism which is sturdy and may be constructed in thefield, and which is economical to fabricate.

Other objects and a more complete understanding of the invention may behad by referring to the following specification and claims taken inconjunction with the accompanying drawings in which:

FIG. 1 is a plan view of apparatus constructed in accordance with thepresent invention;

FIG. 2 is a side elevational view of the apparatus illustrated in FIG.1;

FIG. 2a is a fragmentary sectional view taken along line 2a-2a of FIG.2;

FIG. 2b is a fragmentary sectional view taken along line 2b-2b of FIG.2; and

FIG. 3a 3d are stick figures illustrating the position of the trussmechanism illustrated in FIGS. 1 and 2 when the first support ispositioned in its nested condition (FIG. 3a); in its extended positionin one direction (FIG. 3b); in its extended position in the oppositedirection (FIG. 30); and when in a nested position with a plurality oflike truss mechanism and extended, as in FIG. 3c, to make steps.

Referring now to the drawings, and especially FIGS. 1 and 2 thereof, akinematic extensible truss mechanism 1 constructed in accordance withthe present invention is illustrated therein. To this end a first set oftruss members 10 is arranged in a parallelogram with pivots 1 1, 12, 13,and 14 at each of the junctures of the truss members 15, 16, 17, and 18.A second set of truss members 20, in the present instance equal inlength to the set of truss members 10, is also arranged in aparallelogram with pivots 21, 22, and common pivots l3 and 14 at thejunctures of truss members 23, 24 and 25. As shown truss member 18, inthe present instance, is common to both sets of truss members.

Inasmuch as the pivot 13 is common to the truss members 17 and 25, whilethe member 17 is pivoted at its lower or remote end to the truss member16, and member 25 is pivoted at its remote end by a pivot 22 to itsparallel truss member 24; and truss members 15 and 23 have a commonpivot at 14, with their remote or lower ends pivoted respectively to themembers 16 and 24 by pivots 1 l and 21, it is easy to see that relativemotion may occur between the truss member 16 and truss member 24. Thusin effect the truss member 16 acts as an outboard support which may beplaced on the ground, or other stationary object while truss member 24operates as a support or platform and may be moved relative to themember or support 16. Of

course, support 24 could also be fixed and support 16 permitted to bemoved.

In order to lend support to the structure of mechanism 1, an identicalpair of sets of truss members is provided on the opposite edge of theplatform 24 with identical pivot points (aligned with the pivot pointsof the first and second set of truss members) which truss members andpivots have been designated with prime numbers corresponding to the basenumbers heretofor given. As shown in FIG. 1 the pivots 21' and 22' jointhe second set of truss members to the support 24, the truss members 23and 25' being pivotally connected to the pivots 21' and 22'respectively.

In accordance with the invention, means are provided to maintainparallelism of the first support 16 with the second support 24 when thesecond support is moved relative to the first support, as indicated bythe direction of the arrow 26 in FIG. 1. To this end, a rigid extension30 is connected to one of the upstanding truss members of the second set20, in the illustrated instance to the truss member 25, andsubstantially at right angles thereto, the extension being alsopivotally connected as by the pivot 13 such that as the member 25,connected to the second support 24, moves, the extension rotates aboutthe pivot 13. Additionally, pivotally connected to the extension 30 asby a pivot 31 is an arm 32 which is also mounted for rotation at itsopposite longitudinal end by the pivot 11. As before, a like extension30' is connected to the upstanding truss member 25' as by the pivot 13and is pivotally connected as by a pivot 31' to an arm 32' which isconnected to pivot 11' of the first set of truss members on the oppositeside of the support 26. In this manner support and rigidity are added tothe mechanism.

For the purposes of this application, it should be recognized that anypermanent or fixed structure or other base member may replace the trussmember 16, as heretofor described in FIGS. 1 and 2, so as to form thefourth side of the parallelogram, and thus truss member" should beconsidered the ground or base upon which the pivots 1'1 and 12 areaffixed. The operation of the mechanism of the present invention is bestillustrated in the stick drawings of FIG. 3a-3c wherein the support 16or one side of the parallelogram of the first set of truss members isconsidered a base, norm or ground level. Referring now to FIGS. 3a-3c,the mechanism is shown in FIG. 3a in its nested or home position, inside elevation. As the support 24 is moved in the direction of the arrow33, (FIG. 3b), members and 17 of the first set of parallelograms, remainparallel to each other while the common truss member 18 remains parallelto the ground or base support 16. As shown the rigid extension 30 movescounterclockwise with respect to pivot 13 while the arm 32 tends to movetowards the vertical. Additionally, truss members and 23 tend to remainparallel, and the action of the extension and arm 32 compensates for thenatural tendency of the support 24 to raise. Therefor, as shown in FIG.312, up to the point that pivot 22 aligns with pivot 11 (as shown inFIG. 3b) support 24 remains parallel to support 16 and there is noelevation of the support 24. In a like manner, when the support 24 ismoved in the direction of the arrow 34 (see FIG. 3c) truss members 15and 17 tend to remain parallel and extension 30 rotates in a clockwisedirection about pivot 13, truss member 25 extending and effecting, incooperation with truss member 23 of the second set, an elevation of thesupport 24. Elevation of the support 24 will continue until the arm 32is slightly over center with respect to the rigid extension 30 and pivot31.

Another way to look at the apparatus of the present invention is that itcomprises a fixed support 16 and a moveable support 24, and at least afirst pair of upstanding truss members 17 and 25 which are joinedadjacent one end of each by pivot means 13. Pivot means 12 join thetruss member 17 adjacent its opposite end to the fixed support 16, whileseparate pivot means 22 join the other of the truss members 25 adjacentits opposite end to the moveable support 24. A second pair of trussmembers 15 and 23 are axially spaced from the first pair of trussmembers and include pivot means 14 joining the truss members of thesecond pair of truss members. The opposite ends of each of the trussmembers 15 and 23 are respectively connected to the fixed and moveablesupport as by separate pivot means, i.e., truss member 15 is connectedto pivot 11 and truss member 23 is connected to pivot 21. A rigidextension 30, extends perpendicularly from one of the truss members, inthe present instance the truss member 25, and an arm 32 extends from theextension 30 to the other of the supports (pivot 11) and is pivotallyconnected adjacent its opposite ends to both the extension and the othersupport.

Thus the mechanism of the present invention permits the maintenance ofcoparallelism with regard to the support 16 and 24 when relative motionoccurs between the truss members. Additionally, when the support 24 ismoved relative to the support 16 in one direction, there is no elevationof the support 24 relative to the support 16 while movement in theopposite direction permits elevation of the support 24 relative to thesupport 16.

It should be recognized that with the rigid extension 30 and arm 32, thetruss member 18 may be disregarded especially if the mechanism is to beused for light duty purposes. However, the structural integrity of themechanism is enhanced with regard to longitudinal instability byemploying the common brace truss member 18.

In order to maintain parallelism of the support 24 rel ative to thesupport 16, at least intermediate the pivots, it is desirable that therigid extension 30 of the truss member 25 of the second set of trussmembers 20 be approximately 50 percent (in length) of the distancebetween the pivots 13 and 14. Although other ratios will work, maximumextension while maintaining parallelism is effected.

It should be recognized that the structure has many uses. For example,the support 24 may be a drawer or the like which may be moved outwardlywithout drooping of the forward end, (extended end) such as illustratedin FIG. 3b. A structural analysis of the apparatus shows that increasedpressure on the extended support or platform tends to cause an inwardmovement of the common truss members 18 and 18, i.e., towards eachother. If loading, therefore, is severe, a brace or braces may beemployed intermediate the common truss members to maintain theirseparation.

Additionally, inasmuch as the support 24 tends to elevate when extendedin the opposite direction, the structure may be useful for loading orunloading docks, ships, loading ramps, etc., or in other circumstanceswhere it would be advisable to have a structure which would permit theloading and unloading from one level to another.

It should also be recognized that the structure lends itself, with asmall ramp at either end of the movable support 24, to being used as aportable bridge which may be easily constructed in the field.Additionally, as illustrated in FIG. 3d, an inversion of the structurewith a plurality of mechanisms 50, 60, etc. may be provided in a nestedposition, each of the base pivots being connected in a vertical plane asat 51, 52, etc., to separate movable platforms 53 and 54 so that eachwill extend from the base or home or nested position with their supportslower than the next superimposed adjacent support, thereby formingsteps.

Although the invention has been described with a certain degree ofparticularity, it is understood that the present disclosure has beenmade only by way of example and that numerous changes in the details ofconstruction and the combination and arrangement of parts and the modeof operation may be made without departing from the spirit and the scopeof the invention as hereinafter claimed.

What is claimed is: v

l. A kinematic extensible truss mechanism, comprising in combination: afixed support and a movable support; at least a first pair of upstandingtruss members joined adjacent one end of each by pivot means; pivotmeans joining one of said truss members adjacent its opposite end tosaid fixed support, and separate pivot means joining the other of saidtruss members adjacent its opposite end to said movable support; asecond pair of truss members axially spaced from said first pair oftruss members and including pivot means joining said one truss member tosaid second truss member, the opposite ends of said truss members beingrespectively connected to said fixed and movable support by separatepivot means; a rigid extension projecting perpendicularly from one ofsaid truss members connected to one of said supports, and an armextending from said extension to the other of said supports andpivotally connected adjacent its opposite ends to both said extensionand said other support.

2. Apparatus in accordance with claim 1 including means to maintainaxial stability of said pairs and their positions, one pair with respectto the other pair.

3. Apparatus in accordance with claim 2 including a truss memberconnected intermediate said pivots joining each pair of truss members,one to the other.

4. Apparatus in accordance with claim 1 wherein the length of said rigidextension is approximately one-half the distance between the pivotsjoining the first and second pair of truss members.

5. A kinematic extensible truss mechanism comprising a pair of sets oftruss members each set of truss members arranged in a parallelogram andpivot means pivotally connecting adjacent truss members of a set, eachset of parallelograms having truss members equal in length to like trussmembers of the other set; a truss member common to each of said sets andpivotally connected adjacent its ends to truss members of each set; anextension of one truss member of said second set of truss membersprojecting at substantially right angles with respect thereto, and anarm pivotally connected to said extension and the diagonally oppositepivot means of said first set of truss members with respect to the pivotmeans of said one truss member.

6. Apparatus in accordance with claim 4 wherein said rigid extension hasa length between pivots approximately one-half the distance between thepivots of said common truss member.

7. A kinematic extensible truss mechanism, comprising in combination: afirst set of truss members arranged in a parallelogram, and pivot meansat each of the junctures of said truss members; a second set of trussmembers arranged in a parallelogram, and pivot means at each of thejunctures of said truss members; at least two of said pivot means ofsaid first set corresponding to two of said pivot means of said secondset; at least one rigid extension from one of said truss members of saidsecond set and an arm pivotally connected to said rigid extension andconnected for rotation to a pivot of said first set of truss memberswhich is not common to said first and second set of truss members,whereby movement of said truss members of one of said sets relative toanother member of the other of said sets maintains parallelism of saidone truss member to the other when relative motion occurs therebetween.

8. Apparatus in accordance with claim 7 wherein when one of said trussmembers of said second set moves in one direction the height of said onetruss member remains constant with respect to the parallel truss memberof said first set.

9. Apparatus in accordance with claim 8 wherein when relative motionoccurs in the opposite direction, said one truss member elevates withrespect to the parallel truss member of said first set.

10. Apparatus in accordance with claim 7 wherein said rigid extension isdisposed substantially at right angles to said one of said truss membersof said second set.

11. Apparatus in accordance with claim 10 wherein said rigid extensionhas a length between pivots approximately one-half the distance betweenthe pivot means common to both said first and second set.

1. A kinematic extensible truss mechanism, comprising in combination: afixed support and a movable support; at least a first pair of upstandingtruss members joined adjacent one end of each by pivot means; pivotmeans joining one of said truss members adjacent its opposite end tosaid fixed support, and separate pivot means joining the other of saidtruss members adjacent its opposite end to said movable support; asecond pair of truss members axially spaced from said first pair oftruss members and including pivot means joining said one truss member tosaid second truss member, the opposite ends of said truss members beingrespectively connected to said fixed and movable support by separatepivot means; a rigid extension projecting perpendicularly from one ofsaid truss members connected to one of said supports, and an armextending from said extension to the other of said supports andpivotally connected adjacent its opposite ends to both said extensionand said other support.
 2. Apparatus in accordance with claim 1including means to maintain axial stability of said pairs and theirpositions, one pair with respect to the other pair.
 3. Apparatus inaccordance with claim 2 including a truss member connected intermediatesaid pivots joining each pair of truss members, one to the other. 4.Apparatus in accordance with claim 1 wherein the length of said rigidextension is approximately one-half the distance between the pivotsjoining the first and second pair of truss members.
 5. A kinematicextensible truss mechanism comprising a pair of sets of truss memberseach set of truss members arranged in a parallelogram and pivot meanspivotally connecting adjacent truss members of a set, each set ofparallelograms having truss members equal in length to like trussmembers of the other set; a truss member common to each of said sets andpivotally connected adjacent its ends to truss members of each set; anextension of one truss member of said second set of truss membersprojecting at substantially right angles with respect thereto, and anarm pivotally connected to said extension and the diagonally oppositepivot means of said first set of truss members with respect to the pivotmeans of said one truss member.
 6. Apparatus in accordance with claim 4wherein said rigid extension has a length between pivots approximatelyone-half the distance between the pivots of said common truss member. 7.A kinematic extensible truss mechanism, comprising in combination: afirst set of truss members arranged in a parallelogram, and pivot meansat each of the junctures of said truss members; a second set of trussmembers arranged in a parallelogram, and pivot means at each of thejunctures of said truss members; at least two of said pivot means ofsaid first set corresponding to two of said pivot means of said secondset; at least one rigid extension from one of said truss members of saidsecond set and an arm pivotally connected to said rigid extension andconnected for rotation to a pivot of said first set of truss memberswhich is not common to said first and second set of truss members,whereby movement of said truss members of one of said sets relative toanother member of the other of said sets Maintains parallelism of saidone truss member to the other when relative motion occurs therebetween.8. Apparatus in accordance with claim 7 wherein when one of said trussmembers of said second set moves in one direction the height of said onetruss member remains constant with respect to the parallel truss memberof said first set.
 9. Apparatus in accordance with claim 8 wherein whenrelative motion occurs in the opposite direction, said one truss memberelevates with respect to the parallel truss member of said first set.10. Apparatus in accordance with claim 7 wherein said rigid extension isdisposed substantially at right angles to said one of said truss membersof said second set.
 11. Apparatus in accordance with claim 10 whereinsaid rigid extension has a length between pivots approximately one-halfthe distance between the pivot means common to both said first andsecond set.